The Production of Terrestrial Meteorites – Moon Accretion and Lithopanspermia

Beech, Martin; Comte, Mark; Coulson, Ian M.

doi:10.11648/j.ajaa.20190701.11

Cited by 7 publications

(2 citation statements)

References 32 publications

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“…At the maximum velocity considered (2.5 km/s), this range was even narrower: from 43° to 59°. Beech et al (2019) noted that due to the atmosphere, only bodies with a diameter of at least 0.7 m…”

Section: Ejection Of Matter From a Cratermentioning

confidence: 99%

Growth of the Moon Due To Bodies Ejected from the Earth

Ipatov

2024

Sol Syst Res

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The evolution of the orbits of bodies ejected from the Earth has been studied at the stage of its accumulation and early evolution after impacts of large planetesimals. In the considered variants of calculations of the motion of bodies ejected from the Earth, most of the bodies left the Hill sphere of the Earth and moved in heliocentric orbits. Their dynamical lifetime reached several hundred million years. At higher ejection velocities v ej the probabilities of collisions of bodies with the Earth and Moon were generally lower. Over the entire considered time interval at the ejection velocity v ej , equal to 11.5, 12 and 14 km/s, the values of the probability of a collision of a body with the Earth were approximately 0.3, 0.2 and 0.15-0.2, respectively. At ejection velocities v ej ≤ 11.25 km/s, i.e., slightly exceeding a parabolic velocity, most of the ejected bodies fell back to the Earth. The probability of a collision of a body ejected from the Earth with the Moon moving in its present orbit was approximately 15-35 times less than that with the Earth at v ej ≥ 11.5 km/s. The probability of a collision of such bodies with the Moon was mainly about 0.004-0.008 at ejection velocities of at least 14 km/s and about 0.006-0.01 at v ej = 12 km/s. It was larger at lower ejection velocities and was in the range of 0.01-0.02 at v ej = 11.3 km/s. The Moon may contain material ejected from the Earth during the accumulation of the Earth and during the late heavy bombardment. At the same time, as obtained in our calculations, the bodies ejected from the Earth and falling on the Moon embryo would not be enough for the Moon to grow to its present mass from a small embryo moving along the present orbit of the Moon. This result argues in favor of the formation of a lunar embryo and its further growth to most of the present mass of the Moon near the Earth. It seems more likely to us that the initial embryo of the Moon with a mass of no more than 0.1 of the mass of the Moon was formed simultaneously with the embryo of the Earth from a common rarefied condensation. For more efficient growth of the Moon embryo, it is desirable that during some collisions of impactor bodies with the Earth, the ejected bodies do not simply fly out of the crater, but some of the matter goes into orbits around the Earth, as in the multi-impact model. The average velocity of collisions of ejected bodies with the Earth is greater at a greater ejection velocity. The values of these collision velocities were about 13, 14-15, 14-16, 14-20, 14-25 km/s with ejection velocities equal to 11.3, 11.5, 12, 14 and 16.4 km/s, respectively. The velocities of collisions of bodies with the Moon were also higher at high ejection velocities and were mainly in the range of 7-8, 10-12, 10-16 and 11-20 km/s at v ej , equal to 11.3, 12, 14 and 16.4 km/s, respectively.

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Section: Ejection Of Matter From a Cratermentioning

confidence: 99%

Growth of the Moon Due To Bodies Ejected from the Earth

Ipatov

2024

Sol Syst Res

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“…A 2 km/s impactor-fragment ejection speed is entirely reasonable in the wake of an initial 20 km/s speed for the crater-forming projectile -the maximum ejecta velocity is generally taken as being much smaller and no more than half of the initial impact velocity [26]. This straightforward, order of magnitude, analysis holds true even in the application of a more rigorous numerical integration of the equations of motion including detailed atmospheric drag effects [27].…”

Section: A Five-way Connectionmentioning

confidence: 99%

The Cape York Meteorites, the Younger Dryas, and Their Possible Association with the Hiawatha and Paterson Impact Craters

Beech¹,

Comte²,

Coulson³

2020

AJAA

Self Cite

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The recent discovery of the Hiawatha and Paterson impact craters in north-western Greenland has motivated three intriguing questions: are they associated with the Cape York meteorites, did they form at the same time, and can one or both of the craters be associated with the abrupt cooling of the Earth, some 10 -13,000 years ago, at the onset of the Younger Dryas. To address the first question, we review the properties of the Cape York meteorites and their associated strewn field. Using the Earth Impact Effects simulator, it is found that the strewn field is generally consistent with the entry of a 2 to 6-m diameter iron asteroid into the Earth's atmosphere some 1 to 2 million years ago. The latter, terrestrial residency age of the meteorites, however, remains preliminary, and further radionuclide analysis is required to confirm the fall epoch. The possibility that the Cape York meteorites are progenitor fragments ejected at the time of crater formation has been investigated with an atmospheric flight program, and while it is possible to account for progenitor fragments traveling the 300-km distance between either crater location and the strewn field, this scenario is deemed unlikely. Indeed, the craters each being in excess of 30-km in diameter would indicate the complete vaporization of the impactors. It is concluded that the Cape York meteorites are unlikely to be related to the formation of either of the craters. Additionally, the 183-km separation between such large craters is remarkable and suggestive of a contemporaneous origin. We investigate this latter possibility, and while it cannot be fully ruled out at the present time, it is, on the basis of Near-Earth Object population statistics, deemed to be highly unlikely that they formed at the same time. This issue, however, will only be fully resolved once improved age estimates become available. Indeed, better crater formation ages will also shed more light upon their possible association with the Younger Dryas onset. With respect to the global climate excursion associated with the Younger Dryas, we review the possibility that the crater progenitor bodies were derived from the Taurid Complex, finding that this scenario is deserving of further study. Moving forwards, however, the conservative hypothesis, that the two craters are temporally distinct, not related to the Cape York meteorites and/or contemporaneous with the Younger Dryas onset, is favored.

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Life on Mars: Past, Present, and Future

Beech

Comte

2021

Terraforming Mars

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The Production of Terrestrial Meteorites – Moon Accretion and Lithopanspermia

Cited by 7 publications

References 32 publications

Growth of the Moon Due To Bodies Ejected from the Earth

Growth of the Moon Due To Bodies Ejected from the Earth

The Cape York Meteorites, the Younger Dryas, and Their Possible Association with the Hiawatha and Paterson Impact Craters

Life on Mars: Past, Present, and Future

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